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ORIGINAL ARTICLE
Year : 2019  |  Volume : 6  |  Issue : 1  |  Page : 21-25

Analysis of retinal nerve fiber layer thickness and visual function in road traffic accident patients with ocular complains


Department of Ophthalmology, King George's Medical University, Lucknow, Uttar Pradesh, India

Date of Web Publication14-Aug-2019

Correspondence Address:
Dr. Pramod Kumar
Department of Ophthalmology, King George's Medical University, Lucknow - 226 003, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/erj.erj_2_19

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  Abstract 

Background: Trauma to eye can cause severe and permanent visual impairment. In some instances there may be vitreous hemorrhage, choroidal hemorrhage, globe rupture and traumatic optic neuropathy. Spectral domain optical coherence tomography (SD-OCT) is a quick, sensitive, non-invasive device that provides high-resolution images of the circumpapillary retinal nerve fiber layer (cp RNFL), yielding reproducible and reliable measurements. Aims and Objectives: TO study visual functions (BCVA, CV, CS) and retinal nerve fiber layer thickness by SD-OCT. Materials and Methods: This was a prospective observational study on 108 patients, performed from Sept 2016 to July 2017. RTA patients with visual loss/visual complaints between ages of 18 – 60 years included. Log Mar BCVA, Colour vision and contrast were noted. RNFL analysis was done by SD-OCT. Results: The mean age was 28.33± 8.70 yrs, There were 19 (17.6%) female, 89(82.4%) male in case group. At first visit, there were significant difference between BCVA, CV and CS between right and left eyes of cases and controls. Significant difference were seen in mean RNFL in right and left eye of cases and control. After follow up,insignificant change in BCVA and CV in both right and left eye. Significant change in CS in both right and left eye. Mean change in RNFL thickness was insignificant. Conclusion: Decrease in visual function occurs following RTA. Also, RNFL thinning occurs which remains persistently thin thereafter.

Keywords: Best-corrected visual acuity, circumpapillary retinal nerve fiber layer, color vision, contrast sensitivity, road traffic accident


How to cite this article:
Singh V, Srivastava RM, Saxena S, Ankita, Kumar P. Analysis of retinal nerve fiber layer thickness and visual function in road traffic accident patients with ocular complains. Egypt Retina J 2019;6:21-5

How to cite this URL:
Singh V, Srivastava RM, Saxena S, Ankita, Kumar P. Analysis of retinal nerve fiber layer thickness and visual function in road traffic accident patients with ocular complains. Egypt Retina J [serial online] 2019 [cited 2019 Sep 18];6:21-5. Available from: http://www.egyptretinaj.com/text.asp?2019/6/1/21/264521


  Introduction Top


Trauma to the eye may cause severe and permanent visual impairment.[1] Ocular trauma may involve the eyelids, lacrimal canaliculi, orbital wall, periorbital structures, conjunctiva, cornea, sclera, and extraocular muscles. In some instances, there may be prolapse of uveal tissue, vitreous hemorrhage, choroidal hemorrhage, and globe rupture.[2] Traumatic optic neuropathy (TON) is also a sight-threatening complication of road traffic accident (RTA) that result in decrease in retinal nerve fiber layer (RNFL) thinning.

Spectral domain optical coherence tomography (SD-OCT) is a quick, sensitive, noninvasive, user-friendly device that provides high-resolution images of the circumpapillary RNFL (cp RNFL), macular volume, macular ganglion cell layer (GCL), and optic nerve head, yielding reproducible, and reliable measurements.

SD-OCT has an axial resolution of 5–7 μm[3] and provides clear imaging of retinal layers thickness that helps in diagnosing optic nerve disorders.


  Materials and Methods Top


This study was a prospective observational study performed at the Department of Ophthalmology, King George's Medical University, Lucknow, Uttar Pradesh, India, from September 2016 to July 2017. The study was performed according to the tenets of Declaration of Helsinki and after approval from the Institutional Review Board. The sample size was calculated as 216, 108 cases, and 108 controls.

The aim of this study was to study clinical profile, visual functions (visual acuity, color vision [CV], contrast sensitivity [CS]), and RNFL thickness (by SD-OCT) of patients presenting with ocular complaints after RTAs, to a tertiary care referral center.

The inclusion criteria comprised of all consenting adult patients (18–60 years) with visual loss/complaints post-RTA. These patients had normal systemic examination and were free from any disability that prevented slit lamp examination.

We excluded patients with media opacity, rupture of globe, diagnosed case of glaucoma, preexisting neurological illness (e.g., cerebrovascular accident, brain tumor, patients on nerve supplements/antioxidants, and patients with spine and pelvic fracture). A detailed history and clinical examination of all cases were done.

Epidemiological details (age and gender), color vision (Ishihara color vision test 37 plate edition), and CS (Pelli-Robson chart) were noted.

Fundus examination was done using slit lamp biomicroscopy using +90D lens and by direct and indirect ophthalmoscope. RNFL analysis was done by SD-OCT (Cirrus HD OCT Carl Zeiss Meditech, Inc., CA, U.S.A version: 5.1.1.6). Optic disc 200 × 200 was used to assess average peripapillary retinal nerve fiber layer thickness measurement.

All RTA patients attending or referred to the department of ophthalmology, outpatient department (OPD), and trauma center were assessed and divided into two groups: RTA patients presenting within the 1st week and RTA patients presenting between 2nd and 4th weeks.

Controls were individuals of similar age and sex attending ophthalmology OPD for refraction. The follow-up was done after 3 months, and at that time, best-corrected visual acuity (BCVA), the evaluation of posterior segment of both eyes was done. OCT RNFL of both eyes was again measured, and average thickness of RNFL was taken for analysis.

Statistical tools

Categorical variables were presented in number and percentage (%), and continuous variables were presented as mean and standard deviation. Quantitative variables were compared using unpaired t-test between the two groups, ANOVA between three groups, and paired t-test used for comparing paired data. A qualitative variable was compared using Chi-square test/Fisher's exact test as appropriate. P < 0.05 was considered statistically significant. The data were entered into MS Excel spreadsheet, and the analysis was done using Statistical Package for Social Sciences version 21.0 (SPSS Inc., Chicago, IL, USA).


  Results Top


A total of 108 patients were enrolled in the study. The baseline demographic data of these patients are depicted in [Table 1]. The mean age was 28.33 ± 8.70 years and 27.0 ± 7.96 years in the cases and controls, respectively. There were 19 (17.6%) female and 89 (82.4%) male in case group and 23 (21.3%) females and 85 (78.7%) males in control group. No statistically significant difference was found (P = 0.784 and P = 0.492, respectively). There was a male preponderance in our study. Visual functions and RNFL thickness of cases at first visit are summarized in [Table 2]. The mean BCVA at the time of presentation was 0.24 ± 0.32 and 0.19 ± 0.23 for right eye and left eye, respectively. The mean CS was 1.26 ± 0.29 and 1.27 ± 0.29 for right eye and left eye, respectively. Mean CV was 0.82 ± 0.16 and 0.80 ± 0.15, respectively. The mean RNFL thickness of the right eye and left eye was 92.81 ± 11.38 and 93.52 ± 10.4, respectively. Statistically insignificant difference was found in visual function and all the quadrants between both the eyes. The analysis of BCVA, CV, CS, and RNFL thickness between cases and controls is summarized in [Table 3]. As shown in [Figure 1] and [Figure 2], there was significant difference between BCVA, CV, and CS between right and left eyes of cases and controls. Significant difference was seen in mean RNFL in the right and left eye of cases and controls (P ≤ 0.001, P ≤ 0.001, respectively). RNFL thinning was found in nasal and temporal quadrant of both right and left eyes (P = 0.001 of each, respectively) and in left superior (P = 0.027) and insignificant change in the right superior quadrant (P = 0.672). Significant change was seen in right inferior (P = 0.001) and insignificant in left inferior quadrant (P = 0.275). Change in visual function and RNFL thickness after follow-up is summarized in [Table 4] and [Figure 3]. Insignificant change in BCVA and CV after 3 month in both right and left eyes (P = 0.549, P = 0.642 and P = 0.076, P = 0.129, respectively). Significant change in CS in both right and left eyes (P = 0.048 and P = 0.036, respectively). Mean change in RNFL thickness was insignificant (P = 0.06 and P = 0.08, respectively). Insignificant change was also seen in right and left nasal inferior and temporal quadrant, respectively. Superior quadrant shows a significant change in mean RNFL thickness in the right and left eye (P = 0.001 and P = 0.009, respectively).
Table 1: Age- and sex-wise distribution of study population

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Table 2: Visual functions and retinal nerve fiber layer thickness of right eye and left eye among cases (n=108)

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Table 3: Comparative analysis of best-corrected visual acuity, color vision, contrast sensitivity, and retinal nerve fiber layer thickness among cases and controls at presentation

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Figure 1: Comparison of visual function of cases and controls in road traffic accident patients with ocular complaints

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Figure 2: Mean retinal nerve fiber layer thickness among cases and controls

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Table 4: Change in visual function and retinal nerve fiber layer thickness after follow-up

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Figure 3: Quadrant-wise retinal nerve fiber layer thickness among cases and controls

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  Discussion Top


A total of 108 patients of RTA were studied, 82 patients came for follow-up, and 26 patients were lost to follow-up. The RTA was more common in young adults with a mean age of 28.33 ± 8.705 years. This was similar to that reported in literature; Ezegwui[1] had reported the peak age between 16 and 30 years in his study. Armstrong et al.[4] and Arora et al.[5] have also reported similar results. In our study, male patients were 82.4% and female patients were 17.6%. Males were more commonly involved in RTAs. Male to female ratio was 5:1 in our study.

Clinical attribute at the time of presentation

The visual acuity after trauma ranged from 6/6 to PL. Most of the patients had visual acuity ranging from 6/9 to 6/36, who had sustained ocular adnexal injury. Decrease in visual acuity occurred due to corneal abrasion, tear film instability, intraocular hemorrhage, and retro-orbital hemorrhage.

Analysis of visual function

In our study, there was a significant decrease in visual acuity as compared to controls. Similar decrease was also found in CS and CV. In our study, 56 (52%) patients had periorbital ecchymosis, edema and subconjunctival hemorrhage were the most common form of injury. Seventeen (16%) patients had isolated subconjunctival hemorrhage were the second-most common form of injury. Four patients had lid fracture. Closed globe injury was the most common than open globe injury similar to reported by Mittal et al.[6] and Arora et al.

Several studies have reported that retinal layer thickness decrease following optic nerve injury. Kanamori et al.[7] reported a decrease in thickness of the entire retina, cp RNFL, and retinal ganglion cell (RGC) complex at 2, 3, 4, and 20 weeks after trauma in four patients. Cunha et al.[8] also investigated that there was a progressive decrease in macular and cp RNFL thickness over the first 12 weeks following TON in three patients. However, most studies had small sample sizes and did not evaluate the morphological change in the retina and visual function in patients with TON. No studies have evaluated all the RTA patients. Therefore, we conducted this study on RTA patients and subsequent follow-up to find out the change in visual function and circumpapillary RNFL thickness measurement using SD-OCT.

We demonstrated that there was significant peripapillary RNFL thinning in both eyes of RTA patients when compared with the eyes of healthy individuals. In patient of trauma, damage of nerve fiber occurred. Therefore, we evaluated the nerve fiber layer thickness to asses all possible changes in RTA patients.[9],[10],[11],[12] Sarkies N et al, find out a strong correlation between RGC density and retinal layer thickness, and reported an exponential decline in the number of ganglion cells and significant thinning of RNFL thickness on SD-OCT following optic nerve injury in mice.[13] These morphological changes detected by SD-OCT have also been reported in humans.

Kanamori et al. reported that cp RNFL and GCL thicknesses remain stable within 1 week after trauma but start to decrease thereafter. Cunha et al. reported a 12% reduction in macular thickness over 5 weeks in patients of TON.

With the time, morphological changes in the retina occur. The optic disc becomes progressively pale and atrophic 3–5 weeks after trauma. At the timing of the first visit, we did not detect any significant change in optic nerve head on the fundus examination or the disc SD-OCT. We detected a tendency for mean cp RNFL thickness to decrease as compared to controls at the time of presentation. Whereas there was a marked reduction in RNFL thickness occurred in outer nasal and temporal quadrant of both eyes and outer superior quadrant of left eyes and temporal quadrant of right eyes. This neurodegenerative progression observed in early TON may occur due to early loss of RGC soma.[1] Munguba et al. reported that RGC soma count decreases initially faster than NFLin vivo as an overall measurable change following optic nerve injury in animal.

In our study, we also found that a significant decrease in visual function such as BCVA, CV, and CS occurred that can be correlated to the structural damage to the retina. A similar study was also done by Ju-Yeun Lee et al. and demonstrated the similar changes in RNFL thickness and in visual function.

When we did the RNFL thickness measurement after follow-up found that the mean RNFL thickness was decreases as compared to controls, but these decrease were not statistically significant. We also found that significant change in RNFL changes occurred in superior quadrant in both the eyes and inferior quadrant of the left eye. These losses were likely to that of occurred in glaucomatous damage in which large damage occurred in superior and inferior areas as compared to other areas. Similar results were also observed by Ju-Yeun et al. In glaucoma, the arcuate fiber passing through superior and inferior portion of lamina cribrosa is generally known as most vulnerable zone due to less connective tissue support, whereas the temporal portion is the last to damage. On follow-up, there were decreased in visual acuity, CV, and CS, but statistically insignificant difference was observed.


  Conclusion Top


Decrease in visual function occurs following RTA. Furthermore, RNFL thinning occurs which remains persistently thin thereafter.

Acknowledgments

I would like to acknowledge the cooperation of residents of ophthalmology department of King George's medical university who participated in data collection and evaluation of the patient.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Ezegwui IR. Eye injuries during road traffic accidents at Abakaliki, Nigeria. Int J Ophthalmol 2004;4:985-8.  Back to cited text no. 1
    
2.
El Shtewi M, Shishko MN, Purohit GK. Road traffic accidents and ocular trauma: experience at Tripoli eye hospital, Libya. Community Eye Health 1999;12:11.  Back to cited text no. 2
    
3.
Seibold LK, Mandava N, Kahook MY. Comparison of retinal nerve fiber layer thickness in normal eyes using time-domain and spectral-domain optical coherence tomography. Am J Ophthalmol 2010;150:807-14.  Back to cited text no. 3
    
4.
Armstrong GW, Chen AJ, Linakis JG, Mello MJ, Greenberg PB. Motor vehicle crash-associated eye injuries presenting to U.S. emergency departments. West J Emerg Med 2014;15:693-700.  Back to cited text no. 4
    
5.
Arora AS, Bhargava G, Chauhan A, Singh P. Ocular trauma in road traffic accidents: Experience at Mathura Das hospital, Jodhpur (Rajasthan). Rajasthan J Ophthalmol 2011;3:1-3.  Back to cited text no. 5
    
6.
Mittal G, Singh N, Suvarana S, Mittal SR. A prospective study on ophthalmic injuries related to maxillofacial trauma in Indian population. Natl J Maxillofac Surg 2012;3:152-8.  Back to cited text no. 6
[PUBMED]  [Full text]  
7.
Kanamori A, Nakamura M, Yamada Y, Negi A. Longitudinal study of retinal nerve fiber layer thickness and ganglion cell complex in traumatic optic neuropathy. Arch Ophthalmol 2012;130:1067-9.  Back to cited text no. 7
    
8.
Cunha LP, Costa-Cunha LV, Malta RF, Monteiro ML. Comparison between retinal nerve fiber layer and macular thickness measured with OCT detecting progressive axonal loss following traumatic optic neuropathy. Arq Bras Oftalmol 2009;72:622-5.  Back to cited text no. 8
    
9.
Liu Y, McDowell CM, Zhang Z, Tebow HE, Wordinger RJ, Clark AF. Monitoring retinal morphologic and functional changes in mice following optic nerve crush. Invest Ophthalmol Vis Sci 2014;55:3766-74.  Back to cited text no. 9
    
10.
Munguba GC, Galeb S, Liu Y, Landy DC, Lam D, Camp A, et al. Nerve fiber layer thinning lags retinal ganglion cell density following crush axonopathy. Invest Ophthalmol Vis Sci 2014;55:6505-13.  Back to cited text no. 10
    
11.
Rovere G, Nadal-Nicolás FM, Agudo-Barriuso M, Sobrado-Calvo P, Nieto-López L, Nucci C, et al. Comparison of retinal nerve fiber layer thinning and retinal ganglion cell loss after optic nerve transection in adult albino rats. Invest Ophthalmol Vis Sci 2015;56:4487-98.  Back to cited text no. 11
    
12.
Chauhan BC, Stevens KT, Levesque JM, Nuschke AC, Sharpe GP, O'Leary N, et al. Longitudinal in vivo imaging of retinal ganglion cells and retinal thickness changes following optic nerve injury in mice. PLoS One 2012;7:e40352.  Back to cited text no. 12
    
13.
Sarkies N. Traumatic optic neuropathy. Eye 2004;18:1122.  Back to cited text no. 13
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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